Best t-amp capacitors?

[cotdt]

Tweeters couldn't play high RF frequencies can they? And that wouldn't damage the tweeter either will it? And wouldn't such high frequencies be completely inaudible? And hey, maybe they might even make the sound better!

 

[serengetiplains]

There's no question the caps degrade the sound to some degree, and really only improve the output if they diminish something (RF) that degrades the output more than the caps do.

 

[Pano]

Pano, what problems could you encounter with that extra RF?

Well Tom, do remember that little girl named Pandora?

This should really be in a thread by itself, but here goes.

It's hard to say what harm the extra RF might do. Maybe none, if there isn't much of it. But if it gets into the signal lines in your amp or amy preamp or CD player, it won't sound good - I've done the test.

Would it hurt the tweeters or the crossovers? Probably not, again if it is not too excessive. But without a filter at all, it would most likely burn out a tweeter. I doubt that any tweeter can reproduce frequencies that high, but they can soak up the RF energy. What is the impedance of tweeters at 700 kHz? I've measured one pair of 4 ohm tweeters and they seem to have an impedance of 15 ohms at 700 kHz. Who knows what others are like?

Which brings us to another issue. There is a lot of reaction between the output transistors and the filter coils. That's why the diodes are there, to help kill voltage overshoot that can damage the transistors. It's a serious matter with class-d amps. How much would going to a simpler filter change the overshoot? I don't know, but it's worth looking at.

What I do know is that changing the inductors in the output filter can really change the sound of the amp. It can also make a big difference in how much RF is on the speaker lines, even with the exact same component values. E.G., my modified Fenice board has 12 dB less RF than the stock Sonic - with what is the same filter on paper. Sounds a lot better too. So knowing that, perhaps I could remove the caps from the Fenice and still be 6 dB ahead of the Sonic. It's worth a try and a listen.

Not surprisingly the output filer of the class-d amp has a great influence on audio quality. It's where we separate the AF from the RF - and the men from the boys. Lots of work to be done here. Not too many people doing it, or at least talking about it.

 

[Lostcause]

This should really be in a thread by itself, but here goes..........

Good stuff Michael
This is far better than reading books and you really make things easy to understand. I do have your ferrite beauties on the outputs and they certainly make a difference.
I'm keen to make the signal path as pure as possible so I may just have a go myself and have a listen.
I have my signal straight from the CD's DAC through your Classic mod, so I can't do any more at the front end that's for sure.

You also talked about changing the quality of the output caps and although this could make an improvement, no caps could still be better. I have no tweets just Full range with a BSC so it may just work.......

edit: I took out the BSC so there will be no protection from that RF......Hmmm

Lee

 

[Pano]

Hi Lee,
I'm glad that someone enjoys my late night ramblings.

Back to the subject of this thread. How are those Obbligato caps treating you? They sound good to me, but maybe a little too mellow?

When I first got them running on a Fenice board with my special toroids I thought something was wrong. Sounded like the hi end was way rolled off - like the amp was slightly muffled - maybe too smooth. Further listening convinced me that there wasn't a lack of detail at all, just a lack of harshness. It was hard to tell on rock and jazz, but classical pieces really have a wealth of micro detail that lets you hear the concert hall.

A friend of mine in California has the amp at the moment, he claims it has hi-end roll off too. He is listening to the amp on Altec 605s coaxials (some of the best drivers ever made) and a pair of Tang Band 2 ways he is designing for me. But I swear, I measured the frequency response and it actually rises at the top end!

So is this a case of clearing up distortion that leaves us feeling that something is missing? You read about this sort of thing in reviews.

What do you think, Lee? Or anyone else.

 

[Lostcause]

Hi Lee,
I'm glad that someone enjoys my late night ramblings.

What do you think, Lee? Or anyone else.

I know what you mean because a pair of full ragers doesn't exactly emphasise the high end! I was going to add some tweets but I kinda like the sound...very easy to listen to..
That's what I like about this simple system...the detail at low levels is incredible!
Taking out the BSC helped the upper end by emphasising it more, OK it may be slightly out of phase on my MLTL's but I'm happy enough.

Are the Obs better than others?...I've only tried the stock and some Solens I had handy so I can't really comment but I sure do like em!

Lee

 

[mofy]

Yes, Brian is correct. You can only get so close, because of the size of the caps. He left his leads long for testing.

Here is a photo of a modified Sonic I did long ago. (I don't modify Sonics anymore, I do other boards).

The yellow caps are Auricaps for the inputs. The large black cap is a 10000uF Nichicon Gold Tune on the power rails. You can try something like this.

An externally hosted image should be here but it was not working when we last tested it.

Nice job. and you replaced the L3, L4, L5, L6.
Dose any improved of the sound ?

 

[serengetiplains]

Pano, thanks for your thoughts, which I read with interest. For those wanting to experiment with teflon caps, which will give better performance than polypropylene caps, I notice that Solen sells metallized varieties. I've used metallized teflons before, though not the Solen brand, and found them to be almost as good as foil teflons. The metallized versions are smaller and cheaper, though still rather more expensive than polypropylenes.

Solen Metallized Teflon Capacitors

 

[cotdt]

Pano, you are amazing.

How about using Sonicaps Platinums, or even better: fluorinert capacitors, though you'd have to roll your own.

 

[serengetiplains]

The Sonicaps are probably very good. I use V-Caps, myself. Though I'll probably switch to fluorinerts and/or porous teflons ...

 

[Pano]

you replaced the L3, L4, L5, L6.
Dose any improved of the sound ?

Oh yes! Maybe bigger than the input caps. The stock inductors on the Sonic are not very good, they don't work well at the frequency range (wrong type of ferrite) and I guess that they are adding a lot of distortion in the audio band. That's why so many people report great results with the air core inductors, low distortion.

For those of you with AMP3 or AMP6 kits, you will recognize the inductors in the photo above. =)
Now I use a smaller, bettercore that need only 10 turns to get 10uF - sweet! Means I can use my fancy silver coated Teflon insulated wire.

The output filter really does have an effect on the sound quality. The stock filters seem to be harsh compared to what I've been able to do.

So I really do need to start a new thread on this subject. Maybe some of the UCD snobs would even join in.

 

[Pano]

For those wanting to experiment with teflon caps

Thanks for the Solen Teflon link, Tom. I've used Solen caps for over 20 years, ever since I got started building Hi-Fi in Paris. Nice product. Haven't tried the Teflon flavor yet.

I did find a another French manufacturer of Teflon caps and tried to talk them out of a few samples. So far, no luck. The Solens are probably as good or better. Will have to give them a listen.

Teflon should be good for an input cap. The sound wil just slip right thru!

 

[filholder]

I am just considering changing the input coupling caps on my amp 3.

I have got some Wima MKS 2.2uf and also some LCR MKT 1.0 UF(got 4 so i would double them up.

The spec sheet are here:_

http://www.lcrcapacitors.co.uk/7.pdf

and here:-

http://www.wima.com/navig/mks2.htm

anyone ever used either and what would be preferable?

As film caps i expect that either would probably be better as coupling caps than the standard panasonic FC's?

any ideas?


phil

 

[BWRX]

You can hope they'd be better (I think they probably would be) but you won't know until you try!

 

[filholder]

Tried the LCRs and i am very happy along with the really beefy SMPS i have just completed based on one of the modules nuuk had for sale the quality of these amps just get better nad better. The Pannt FC's were very much limiting the sound of the amp, sounds a lot faster now. Frequnecy response and the very high and low level seems sharper too me while not sounding harsh. Hard to say in total but this week i have added some BHC/ panny FC supply caps added the 6amp SMPS and replaced the input coupling caps. Sounded better with every tweak.

I know other rave about the chalize and i am sure they are nice but i just love the amp3 for value it has to be the best in the world, better even than the SI cos i has a similar sound but far less limitations.

 

[irss]

I still haven't found the information regarding the cap in the middle of the board. Is changing the cap in the middle really worth the effort? Because this specific mod is rather difficult... does it really improve the sound?
This kind of mod is not provided in panomaniac webstite (which I regard as a best t-amp mod site on the web), therefore I presume, it is not really worth the effort, is it?


a bit off topic question...:

could anyone please advise, what wires should I chose in order to change original t-amp wiring....or should I leave the original wires? Some people say that due to the fact that this is 2x15W amp, changing internal wiring does not make sence...:/

 

[Pano]

This kind of mod is not provided in panomaniac webstite

Oh? I thought it was. Might be buried in there somewhere. I'll have to look.

But yes, it IS important. A must do. Not hard to do, either. Just unsolder and pull it out like a rotten tooth. A Panasonic FC, or better yet FM, does well there. Try 680uF 16V.

 

[Pano]

I have got some Wima MKS 2.2uf

One of the T-amp modders in France reported that he liked Blackgates better than the Wima. I don't think much of the Blackgates, so.... I think he went on to some better film cap, maybe Solen. Don't know which type of Wima he had.

Try a few different types, they all seem to sound a little different. Find what you like. Be careful not to be blinded by "bright" sounding caps thinking they have more detail. Usually they don't, they're just bright. Listen for the micro details that define the recorded space, that's a good hint to detail and accuracy. Classical is a good test for that.

 

[irss]

Oh? I thought it was. Might be buried in there somewhere. I'll have to look.

But yes, it IS important. A must do. Not hard to do, either. Just unsolder and pull it out like a rotten tooth. A Panasonic FC, or better yet FM, does well there. Try 680uF 16V.

Thanks Pano. I've seen few posts, where people claim that the larger the better... So, i suppose, if size does not matter (it will be installed off the board) it is advisable to install bigger cap..., for example 10000uF 16V.

Any advises on re-wiring (?)

 

[filholder]

I think it is generally accpeted not to go too big on board. Get a fast 3-400 uf cap on board and them use a 10.000uf cap off board. I did this with both my Sonic impact and my Amp 3 and found it worked very well. If you put a larger slower cap onboard you may get negative effect from it.

This is what i have done anyway, Good FC on board and then a big 10,000 BHC off board. Sounds excellent.